男性,70岁,因上腹部不适、腹胀1月,晨起发现“黑便”就诊。患者曾有“胃病史”5年。为明确诊断,应建议该患者进行的检查是()
A. 腹部B超
B. X线钡餐
C. 纤维胃镜
D. CT
EXCEL中单元格公式引用不正确的是()
A. =A1
B. =SUM(B2:E8)
C. (A2+B2)/C2
D. =AVERAGE($D$3:$D$1000)
The great use of school education is not so much to teach you things _____ to teach you the art of learning.
A. as
B. than
C. but
D. that
在关系代数运算中,五种基本运算为()
A. 并、差、选择、投影、自然连接
B. 并、差、交、选择、投影
C. 并、差、选择、投影、乘积
D. 井、差、交、选择、乘积